Protective coating for a substrate

ABSTRACT

A coating having a gradient composite structure, applied to a substrate, which may be a disposable tool. The gradient composite comprises a bonding component and an erosion and/or corrosion resistant component. When applied to a disposable tool, such as a ball and seat assembly in a downhole environment, the coating enhances the performance of disintegrable materials used in such tools. The coating may be configured to expire at the end of a selected duration, allowing the underlying material to disintegrate.

BACKGROUND

Seat assemblies such as, for example, ball seats, are well known in avariety of industries. In downhole applications, such as in hydraulicfracturing operation, balls or plugs and seats for the same are commonlyused to control the flow of fluids and actuate downhole devices. Whilesuch systems work sufficiently for their desired purposes, theseassemblies can interfere with subsequent operations, activities,production, etc., and physical removal of the seats, e.g., by fishing orintervention, can be difficult, costly, and time consuming. Therefore,the industry is receptive to advancements in ball or plug seat assemblytechnology, particularly in designs that enable the seat and the variouscomponents thereof to be selectively removed in order to facilitatesubsequent operations.

SUMMARY

Disclosed herein is a coating for a transitory substrate. The coating isa composite structure with a bonding component and an erosion and/orcorrosion resistant component. A proximal layer of the coating containsa greater amount of the bonding component in comparison with a distallayer.

Also disclosed herein is a disposable tool including a substrate formedfrom a disintegrable material. The coating has a gradient compositestructure, formed of a bonding component and an erosion and/or corrosionresistant component, with a layer of the coating in contact with thesubstrate having a greater amount of the bonding component than a distallayer.

Also disclosed herein is an apparatus for restricting flow through awell conduit. The apparatus comprises a housing with a seat and a plugmember. The housing and/or the plug member is formed from adisintegrable material with a protective coating applied thereon.

Also disclosed herein is a seat assembly located in a well bore. Theseat assembly is formed with a substrate, at least partially from adisintegrable material.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a sectioned side view depicting a coating on a substrate,according to one embodiment;

FIG. 2 is a graph depicting various examples of a gradient compositestructure according to another embodiment; and

FIG. 3 is a sectioned side view depicting a ball and seat plug assemblyaccording to another embodiment.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures. It is to be understoodthat other embodiments may be utilized and changes may be made withoutdeparting from the scope of the present disclosure. In particular, thedisclosure provides various examples related to a ball seat apparatusfor use in well operations, whereas the advantages of the presentdisclosure as applied in a related field would be apparent to one havingordinary skill in the art and are considered to be within the scope ofthe present invention.

In one embodiment, the present disclosure provides a tool assemblyhaving a substrate that is formed at least partially from adisintegrable material. The tool assembly may be, for example, a seatassembly disposed in a well bore. The seat assembly includes a seatelement configured to receive a plug element, such as a frac ball or thelike, whereupon the seat element and the plug element restrict the flowof fluids through the well bore when the plug element is landed thereon.The advantages of having a tool assembly or an element thereof, such asa seat element, comprised of a disintegrable surface are discussed inmore detail below. In short, the use of a disintegrable material enablesa controllable and predictable disposal. By using a disintegrablematerial, as opposed to a material that can be dissolved in a particularfluid, the tool assembly or tool element may be disposed of in a shortamount of time with accurate results. Some disintegrable materials mayhave an element embedded therein that can be triggered to activate anaccelerated disposal of the structure.

FIG. 1 is an illustration of one embodiment of a protective coatingdisclosed herein. The coating 120 is applied to a substrate 100. Thecoating 120 comprises a gradient composite structure. As shown, thecoating comprises a proximal layer 121, which lies against thesubstrate, and a distal layer 125. In the illustrated example, it willbe appreciated that the coating comprises a plurality of additionalintervening layers between the proximal layer 121 and the distal layer125. Each layer of the gradient composite structure contains increasingamounts of one component and decreasing amounts of the other componentwhen viewed in one direction. The layers may be bonded, fused, orotherwise attached to each other and to the substrate.

In some examples of the present disclosure, the substrate 100 is adisposable tool. The substrate may be a transitory substrate, one thatis configured to be dissolved, decomposed, disintegrated or deformed inorder to dispose of the tool when its purpose has been fulfilled. Insome examples, the transitory substrate may be formed of a disintegrablematerial, so as to eliminate any necessary intervention to dispose ofthe tool. The disintegration of the substrate 100 may be accomplished,for example, by adding a chemical to a process fluid, by raising thepressure and/or temperature of the process fluid, or by prolongedexposure to the environment in which the tool is used. For example, thesubstrate may be formed of a material that will be substantiallydissolved or disintegrated within a particular timeframe, once thesubstrate is exposed to a particular process fluid. In some examples,the substrate itself may comprise an outer layer covering a furtherunderlying structure or applied to an underlying structure or tool. Thesubstrate may, for example, form tool used in a downhole environment,including a plug, a plug seat, disk, dart, sleeve, tubular section, orthe like.

The coating 120 of the present disclosure may be a coating, a film, adeposit, a cladding, or any other layer applied to an underlyingstructure. The coating 120 of the present disclosure can be applied to atool, or to an exposed feature of a tool, to protect the tool fromerosion and/or corrosion until the completion of a particular operation.For example, many disintegrable materials that are presently availabledo not perform as well as other alternative materials used fordisposable tools, such as cast iron. The coating 120 described hereincan be formed to exhibit superior qualities of hardness, toughness, andchemical resistance towards the process fluid, thereby protecting thetool from erosion and corrosion and enhancing the performance anddurability of the disintegrable material. The coatings of the presentdisclosure may inhibit volume loss due to erosion by as much as a factorof 15 when compared to cast iron.

The coating 120 may exhibit other advantageous qualities. The gradientcomposite structure of the coating 120 may be configured to predictablyfail or dissolve within a particular timeframe when used in a chosenenvironment. By selecting materials, gradient compositions andthickness, the coating may be configured to fail, or dissolve in aselected timeframe. Where the coating is applied to a transitorysubstrate, the substrate may be configured to quickly disintegrate uponthe expiration (failure or dissolution) of the coating. Thus, thepresent invention enables the selective use of coatings to enhance theperformance of a particular tool and to more effectively dispose of thetool if desired. The coating may be configured to endure for a selectedduration by changing the composition and/or thickness thereof.

In some embodiments the coating 120 comprises two primary components,namely, a bonding component and an erosion and/or corrosion resistantcomponent. Each of the bonding component and erosion and/or corrosionresistant components may further comprise multiple ingredients. Forexample, the bonding component is selected to bring a quality oftoughness to the coating; i.e., the bonding component enables thecoating to resiliently attach to the substrate as well as form aresilient microstructure, forming a matrix for holding the erosionand/or corrosion resistant component. Examples of materials that may beappropriate for use in the bonding component include cobalt, chromium,copper, nickel, iron, and the like, including alloys thereof. Thesematerials are typically noted for ductility and ability to form strongmetallurgical bonds with disintegrable materials used as substrate fordisintegrable tools. Other materials that may be useful as ingredientswithin the bonding component will be apparent to one having ordinaryskill in the art and are within the scope of the present disclosure.

As described above, the erosion and/or corrosion-resistant component ischosen to enhance the hardness, toughness, and/or chemical resistance ofthe coating. This is intended to protect the substrate from erosionand/or corrosion that may otherwise result from exposure to theenvironment in which the substrate is placed. The erosion and/orcorrosion resistant component may further be chosen to complement thematerial or ingredients chosen for the bonding component. Examples ofmaterials that may be appropriate for use in the erosion and/orcorrosion resistant component of the composite structure includecarbides, nitrides, oxides, ceramics, and intermetallics. More specificexamples include tungsten carbide, silicon carbide, chromium carbide,titanium carbide, zirconium carbide, silicon oxide, aluminum oxide andthe like. Other materials that may be useful as ingredients within theerosion and/or corrosion resistant component will be apparent to onehaving ordinary skill in the art and are within the scope of the presentdisclosure.

In one embodiment the components of the composite structure are presentin increasing or decreasing amounts when viewed from the proximal ordistal layers of the structure. For example, as shown in FIG. 1, theproximal layer contains a greater concentration of the bonding componentwhen compared to the distal layer. Likewise, the erosion and/orcorrosion resistant component may exist in increasing amounts amongsuccessive layers, when viewed from the proximal layer.

The coating 120 may be applied to the substrate 100 using any one of anumber of suitable methods. In many cases, the coating will be appliedas a series of thin layers with the component materials being suppliedin a powder or solid block form. Suitable methods include, for example,physical vapor deposition, chemical vapor deposition, plasma-enhancedchemical vapor deposition, thermal spray, cold spray, or laserdeposition methods. In some embodiments, the material forming thesubstrate may require that the procedure for applying the coating beperformed at or below a particular temperature, which may restrict thenumber of methods available. Whether accomplished using exposure tohigh-temperature, high-pressure, or by another method, the compositecoating forms a resilient microstructure and a sufficient bond with theunderlying substrate.

FIG. 2 displays a chart showing various examples of the composition ofthe gradient composite structure of the present disclosure. Thehorizontal axis corresponds to the fractional depth of the coating, with1.0 representing proximal layer, or the point at which the coatingcontacts the substrate, and with 0.0 representing the outer extent ofthe distal layer. The vertical axis of the chart corresponds to theratio of the bonding component to the erosion and/or corrosion resistantcomponent, with 70/30 representing a composition of 70 parts bondingcomponent to 30 parts erosion and/or corrosion resistant component, forexample.

In FIG. 2, example ‘a’ represents a coating in which the composition atthe proximal layer is a ratio of approximately 88 parts bondingcomponent to 12 parts erosion and/or corrosion resistant component. Thecomposition of the composite structure in example ‘a’ evolvescontinuously on an even gradient to the distal layer, where thecomposition is approximately 25 parts bonding component and 75 partserosion and/or corrosion resistant component. Example ‘b’ of FIG. 2depicts a similar composition in which the concentration of bondingcomponent increases more rapidly near the extent of the distal layer.Example ‘c’ illustrates another case in which a ratio of 20 to 80 ischosen at the distal layer, and a ratio of 70/30 is chosen at theproximal layer. Finally, example d illustrates a case in which thecomposite structure comprises five distinct layers of varying ratios,roughly following the line of example ‘b’.

FIG. 2 does is not intended to convey each of the many ways in which thegradient may vary. A variety of ratios may be chosen for differentapplications, including those in which the layers of the compositestructure are not as distinct as those shown in example ‘d’. Because ofthe small dimensions of many embodiments, the transition zones from onelayer to another in the microstructure of the coating will vary in depthand consistency. Further, any ratios may be chosen for the distal andproximal layers, with the proximal layer typically containing a greaterconcentration of the bonding component. For example, in variousembodiments, the ratio of bonding component to erosion and/or corrosionresistant component was chosen to be anywhere from about 90/10 to about50/50. This ratio may be selected, for example, to achieve a failure ordissolution of the coating after a selected duration or within aselected timeframe.

The thickness of the coating, in addition to the composition thereof, isa significant factor in determining the properties of the coating andthe duration after which the coating will expire. In some examples, thecoating thickness was selected to be within a range of from about 0.0005inches to about 0.1 inches. Other examples were chosen to have athickness of about 0.010 inches, about 0.020 inches, and about 0.060inches, respectively. Larger coating thicknesses are possible, dependingon the materials and the application. Thicker coatings, however may leadto cracking or other defects that can lead to premature failure. Ingeneral, the coating should be at a thickness that can be consistentlyapplied and that will withstand the environment of the chosenapplication, though exceptions, such as an intentional variation inthickness, are also within the scope of this disclosure.

Another important aspect of material selection for the bonding anderosion and/or corrosion resistant components is the coefficient ofthermal expansion. At least the bonding component, if not the compositestructure in its entirety, should have a coefficient of thermalexpansion that is substantially similar to the coefficient of thermalexpansion of the substrate. While it is not required to make a precisematch between the respective materials, selecting materials that aresubstantially similar, such as within 5×10⁻⁶ unit length per ° C.(approximately 2.78×10⁻⁶/° F.), may ensure that the coating remainsintact for the intended duration.

FIG. 3 depicts one embodiment of the present disclosure, employed withan apparatus for restricting fluid flow through a well conduit. In theillustrated example, a ball and seat assembly are deployed in theproduction tubing 260 of a well. The assembly comprises a housing 250arranged in the production tubing 260, with a seat 240 arranged in alongitudinal bore of the housing 250. A ball 200 is illustrated in aposition on the seat wherein the ball 200 restricts fluid flow throughthe longitudinal bore of the housing 250 and the production tubing 260.The features mentioned above are generic to most ball and seatassemblies. In this case any one or more of the ball 200, the seat 240,or the housing 250, may comprise a transitory substrate, which may beformed of a disintegrable material. Other examples of the ball and seatassembly may comprise any number of additional features, any one ofwhich may also be formed with a transitory substrate.

A coating in accordance with the present disclosure may be applied toeach of the features of FIG. 3 that include the transitory substrate.The resulting apparatus exhibits enhanced characteristics of erosion andcorrosion resistance throughout the duration of the life of the coating.The intended duration of the life of the coating may be selected for aparticular application and the composition and thickness of the coatingchosen accordingly.

Upon the expiration of the coating, the ball 200, seat 240, and/orhousing 250, comprising a transitory substrate may be disposed of in aselected timeframe according to the chosen substrate.

The chosen substrate may be any one of a number of materials that arecurrently available or which will become available that are appropriatefor the desired purpose. The transitory substrate may comprise adisintegrable material that includes a disintegration agent activated byexposure to a particular fluid or pH. Examples of a suitable materialinclude controlled electrolytic metallic (CEM) materials, a BHIproprietary material. These lightweight, high-strength and selectablyand controllably degradable materials include fully-dense, sinteredpowder compacts formed from coated powder materials that include variouslightweight particle cores and core materials having various singlelayer and multilayer nanoscale coatings. These powder compacts are madefrom coated metallic powders that include variouselectrochemically-active (e.g., having relatively higher standardoxidation potentials) lightweight, high-strength particle cores and corematerials, such as electrochemically active metals, that are dispersedwithin a cellular nanomatrix formed from the various nanoscale metalliccoating layers of metallic coating materials, and are particularlyuseful in borehole applications. Materials such as these may be pairedwith the erosion and corrosion resistant coating of the presentdisclosure to improve the performance of the material or tool.

The disclosure above describes exemplary embodiments of ball seats.Other embodiments may include any number of ball seats having multipleseat portions, flow paths, alignment planes, and shapes of plug membersthat are operative to direct objects to engage the seats. Further,although the term “ball” is used herein to refer to the seats disclosedherein, it is to be understood that the seats may be used in connectionwith another type of plug or plug member, such as a plug dart. All suchconfigurations are deemed to be within the scope of the presentdisclosure and are deemed to be encompassed by the term “plug member.”

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Also, in the drawings andthe description, there have been disclosed exemplary embodiments of theinvention and, although specific terms may have been employed, they areunless otherwise stated used in a generic and descriptive sense only andnot for purposes of limitation, the scope of the invention therefore notbeing so limited. Moreover, the use of the terms first, second, etc. ,do not denote any order or importance, but rather the terms first,second, etc. are used to distinguish one element from another.Furthermore, the use of the terms a, an, etc. do not denote a limitationof quantity, but rather denote the presence of at least one of thereferenced item.

1. A coating for a transitory substrate, comprising: a compositestructure having a bonding component and an erosion or corrosionresistant component, the composite structure having a proximal layer anda distal layer, the proximal layer being attached to a substrate, theproximal layer having a greater concentration of the bonding componentwhen compared with the distal layer.
 2. The coating of claim 1, thecomposite structure comprising a plurality of layers disposed betweenthe proximal layer and the distal layer, each of the plurality of layersexhibiting a decrease in a ratio of the bonding component to the erosionor corrosion resistant component, when viewed from the proximal layer.3. The coating of claim 1, the substrate being formed of a disintegrablematerial.
 4. The coating of claim 3, the disintegrable materialcomprising controlled electrolytic metallic materials.
 5. The coating ofclaim 1, the bonding component including one or more of cobalt, cobaltalloys, chromium, chromium alloys, copper, copper alloys, iron, ironalloys, nickel, and nickel alloys.
 6. The coating of claim 1, theerosion or corrosion resistant component comprising one or more of acarbide, a nitride, an oxide, a ceramic, and an intermetallic.
 7. Thecoating of claim 1, the composite structure having a thickness that isbetween about 0.0005 to about 0.10 inches.
 8. The coating of claim 1,configured to fail after a selected duration.
 9. The coating of claim 1,a ratio of the bonding component to the erosion and/or corrosionresistant component at the proximal layer being between about 90/10 andabout 50/50.
 10. A disposable tool, comprising: a substrate formed of adisintegrable material; and a coating disposed on an outer surface ofthe substrate, the coating comprising a gradient composite structure,having a bonding component with a greater concentration at a proximallayer, and a composite structure having a bonding component and anerosion or corrosion resistant component, the composite structure havinga proximal layer and a distal layer, the proximal layer being attachedto a substrate, the composite structure having a ratio of the bondingcomponent to the erosion or corrosion resistant component at theproximal layer that is greater than a ratio of the bonding component tothe erosion or corrosion-resistant component at the distal layer. 11.The tool of claim 10, the disintegrable material comprising controlledelectrolytic metallic materials.
 12. The tool of claim 10, the coatingbeing disposed onto the outer surface of the substrate by physical vapordeposition, chemical vapor deposition, plasma-enhanced chemical vapordeposition, thermal spray, cold spray, or laser deposition.
 13. The toolof claim 10, the bonding component having a coefficient of thermalexpansion that substantially matches a coefficient of thermal expansionof the disintegrable substrate material.
 14. The tool of claim 10, thesubstrate comprising a plug, plug seat, disk, dart, sleeve or tubularsection.
 15. The tool of claim 9, the substrate and coating configuredto form at least a part of an apparatus for restricting flow through awell conduit.
 16. An apparatus for restricting flow through a wellconduit, comprising: a housing having a longitudinal bore and a seatdisposed within the bore; and a plug member configured to be disposedinto the bore and landed on the seat to restrict fluid flow through thebore; at least one of the seat or plug member being formed of adisintegrable material and having a protective coating applied thereon.17. The apparatus of claim 16, the protective coating comprising agradient composite structure having a bonding component and an erosionor corrosion resistant component, the gradient composite structurecomprising a proximal layer being attached to a substrate, the proximallayer having a greater concentration of the bonding component whencompared with a distal layer of the gradient composite structure. 18.The apparatus of claim 17, the bonding component including one or moreof cobalt, cobalt alloys, chromium, chromium alloys, copper, copperalloys, nickel, and nickel alloys.
 19. The apparatus of claim 17, theerosion or corrosion resistant component comprising one or more of acarbide, a nitride, an oxide, a ceramic, and an intermetallic
 20. Theapparatus of claim 16, the disintegrable material comprising controlledelectrolytic metallic materials.
 21. The apparatus of claim 16, theprotective coating and the disintegrable material configured todisintegrate each within a selected timeframe.
 22. A seat assemblylocated in a well bore, comprising a seat element having a substrateformed at least partially from a disintegrable material and disposed ina well bore, the seat element being configured to receive a plugelement, the seat element and the plug element restricting flow throughthe well bore when the plug is received by the seat element.
 23. Theseat assembly of claim 22, wherein the disintegrable material comprisescontrolled electrolytic metallic.
 24. The seat assembly of claim 22,further comprising an outer layer deposed on the substrate.
 25. The seatassembly of claim 24, the outer layer formed at least partially from anerosion or corrosion resistant material.
 26. The seat assembly of claim25, the outer layer comprising a gradient composite material formed atleast partially from a bonding material.